The invention is related to rotors for axial flow fluid machines and, more particularly, to a multiple section rotor disk constructed to contain disk failure.
One of the most serious problems facing the designers of modern axial flow fluid machines is that of a major disk failure. The problem is particularly critical for aircraft gas turbine engines, wherein the failure of a single major disk may result in total engine failure due to engine structural damage caused by the pieces of a failed rotor being ingested by the engine or penetrating the engine casings. This problem has been magnified in the gas turbine engines used to power the relatively large wide-bodied aircraft recently introduced into airline service. The greater mass of the relatively large rotor disks utilized in such engines and resultant greater kinetic energy associated with the liberated rotating disk fragments is much more likely to cause total engine failure and major airframe damage.
One proposed solution for reducing failure in rotor disks has been to utilize rotor disks comprised of multiple sections. Typically, such rotor structures have been designed with sufficient extra disk sections such that in the event of a failure of any one disk section, the increased load on the remaining disk sections is not likely to make them fail. While such prior art disk structures have been shown to greatly reduce the probability of a catastrophic turbine disk failure, heretofore, they have not been widely utilized. This lack of acceptance is primarily because the additional weight and installation problems associated with such prior art structures make them extremely uncompetitive. Further prior art laminated rotor disk structures have demonstrated structural weaknesses due to propagation of disk cracks from one section to another. Similarly prior art multiple section disks which have utilized a plurality of radially displaced bolt circles for joining have required increased material for structural reinforcement of the large number of bolt holes as to make them excessively heavy.